Instrument for the production of musical tones forming a tempered scale.



E. G. THOMAS.

INSTRUMENT FOR THE PRODUCTION, OF MUSICAL TONES FORMING A'TEMPERED SCALE.

APPLICATION FILED JUNE 2.1910.

1 Patented Oct. 12, 1915.

' 3 SHEETS-SHEET 1..

E. G. THOMAS. Y INSTRUMENT FOR THE PRODUCTION OF MUSICAL TONES FORMING A TEMPERED SCALE APPLICATION FILED JUNE 2. 1910. 1,156,329. Patented 001121915.

3 SHEETS-SHEET 2.

WED-1:55:25 5.

n %jize E. G. THOMAS.

INSTRUMENT FOR THE PRODUCTION OF MUSICAL TUNES FURNHWK'TEMFEREU'SCALE APPLICATION FILED JUNE 2.1910.

1,156,329. Patented' 0x12, 1915.

3 SHEETS-SHEET 3.

illlllllllllll IHIHIIIII JIIIIIIIIIIHIIIIIIIIH 'Hl'lllllllllll F WEI/255E 5 I fill/5171774 UNITED STATES PATENT OFFICE.

EDWARD G. THOMAS, OF BROOKLINE, MASSACHUSETTS, ASSIGNOR, BY MESNE ASSIGN- MENTS, T0 CHORALCELO COMPANY, OF BOSTON, MASSACHUSETTS, A CORPORATION '01 MAINE.

INSTRUMENT FOR THE PRODUCTION OF MUSICAL TONES FORMING A TEMPERED SCALE.

To all whom it may concern:

Be it known that I, EDWARD G. THOMAS, of Brookline, in the county of Norfolk and State of Massachusetts, have invented certain new and useful Improvements in Inare among the purest and most free from overtones of any which can be made. These notes are consequently the best for aiding the ear of the student-tuner in recognizing differences in pitch in pure musical tones. There is now, however, no instrument of such type which can be so utilized in temperamental tuning. Moreover, the siren as it now exists, inasmuch as it produces intervalswhich are those of the just diatonic scale, naturally is of no value as an aid in teaching tuning in equally tempered scale, since the temperamental beat between cor rectly tuned chords of the equally tempered scale is not present in chords tuned to just diatonic scale, and it is vby this temperamental beat that thetuning isdone. It is of great importance, therefore, to have an instrument giving the correcttemperamental beats as a standard to which the learner may refer for comparison. What I am endeavoring to produce, therefore, is an instrument wherein the pure notes of the siren are combined in so accurate chords in the equally tempered scale as to give pleasure to the ear trained to appreciate temperamental precision, and to assist in training the tuner to realize the possibility of a perfect equally tempered scale.

In carrying out my invention, I prefer to gear together twelve sets of rotating members, or rotors, each adapted to produce pulsations for as many octaves of a note as the instrument is designed to embrace in range. To this end, each rotor will bear a series of interrupting instrumentalities, sald instrumentalities di ering in frequency of their interruptions one to another in a geometrical ratio. The instrumentalities on any one rotor are all associated with the same letter of the musical scale in different octaves and the frequency of the interruptions caused by an instrumentality differs from Specification of Letters Patent.

' Patented Oct. 12, 1915.

that caused by another instrumentality in accordance with the vibrational differences of their respective associated tones. Inasmuch as it is preferable to have the rotors duplicates of eachother, I vary the pitch of their interruptions by giving them different speeds: for' instance, the rotor carrying the ES will have a speed relative to that carrying the Fs in the ratio of one to the twelfth root of two; and so, in like manner, with the rest of the rotors.

Referring to the drawings forming part of this specification, Figure l is a plan view of twelve such rotors geared directly one to another. Fig. 2 is'a diagram of two intermeshing gears adapted for said arrangement. Fig. 3 is a face view of one of the rotors and certain connected devices. Fig. 4 is a face view of twelve rotors, showing a keyboard controlling the blast thereto. Fig. 5 is a plan view of the wind chest and connections. Fig. 6 is a cross section of the wind-chest and connections. Fig. 7 is a detail view of same. Fig. 8 is a perspective view of one of the keys of the key-board. Fig. 9 is a plan view of a form of the instrument wherein the rotors are separately geared to a single operating shaft.

The embodiment of my invention shown in Fig. 1, consists of twelve parallel shafts 1 each provided with a thin disk 2 having openings 8 through them (Fig. 3), designed to move rapidly past an air-blast, delivered from a nozzle 44, and thereby to produce musical tones each tuned to the pitch of some note of the scale. By giving'each disk six annular rows of said openings, as in Fig. 3, a six-octave musical instrument is provided. The shaft 1 here represented as next to and driven by the motor 4:, is the with the gear 7 of the third shaft, and so on through the whole series. As represented in Fig. l, the gears'6 are of larger diameter than the gears 7, but I do not restrict myself to such an arrangement, inasmuch as the motor can as readily be directly connected with the most rapidly rotated shaft, and the others geared down therefrom. The blastproducing means may be of any desired construction; the one illustrated in' Fig. 1 being a rotary blower 8 operated by said motor 4.

'If the instrument is designed for the use of piano and organ tuners during their Work, or for the purpose of training their ears to recognize perfectly tempered scales, the pure tones produced by the coaction of the perforated disks and air-blasts, are much to be preferred; but in case richer tones are desired, as in the production of music, brushes, as 10, may be made to con-tact with the disks 2 and by the current-interrupting effect of the passage beneath them of the openings 3, to communicate electric pulsations to electromagnets 12 in whose fields are 1 located either properly tuned tuning-forks 3. tuned strings 14, or the like, as shown in Fig. 3.

To conduct the air currents to the disks 2, I prefer to provide an elongated box 01. wind-chest 15 to which the air under pressure is communicated, and from which rise twelve sets of siX tubes 16, as in Fig. 6, terminating in narrow mouths close to the disks; each mouth coming to the height of some one of the six annular rows of openings 3. The illustrated method of opening and closing these tubes consists of a valve 17 similar to a stovepipe damper in each tube (see Fig. 7), the externally prolonged shaft 18 of which carries an armatured arm 19 rigid with the same. An electromagnet 20 held by said box, attracts said armature and thereby turns and opens the valve whenever such electromagnet is energized; a tension spring 21 closing the valve when the magnet is demagnetized.

Each key 25 (see 'Fig. 8) carries a contact 26 joined by a common wire 27 to a source of current 28; while immediately aboveeach contact 26 is a fixed contact 29 joined by a wire 30 to the proper electromagnet; all said electromagnets being connected by a common wire 31 to said source of current. Consequently, whenever one or more of said keys are depressed, the proper valves are operated, and the associated rows of perforations given the air currents needed for the production 'of musical tones therefrom.

To reinforce the siren-tones, resonators 35 may be positioned near the disks 2 opposite the mouths of the tubes 16, as shown in Fig. 6; the same being propefly proportioned, or tuned, to resound the respective notes with which they are associated.

The turned strings 14 which may also be associated with and reinforce the siren-tones, are actuated by electromagnets 12, the latter being energized by currents from the source 36, and such currents are rendered intermittent by the brushes 37 suitably supported in the paths of the openings 3. The circuits in each case comprise a wire 39 from said source to a brush 40, shaft 1, disk 2, a brush 37, a wire 41, electromagnet 12 and a common wire 42 back to said source 36; as shown in Fig. 3.

The circuit for the tuning forks 13 already referred to, consists of the wire 12 leading from said source 36 to the electromagnet 12, the wire 43 leading to the brush 10, and the remainder of the circuit comprising the disk 2, brush 40 and wire 39.

In the construction shown in Fig. 9, a single common driving shaft 50 is geared to the shafts 1 on which are mounted the perforated disk or rotors 2, the air under pressure being conducted thereto from the wind-chests 15 through the branches 16 in substantially the same way as before. Each pair of gears 51, 52 by which power is conveyed from the driving shaft to the rotor shafts, differsv quite materially from the pair 6, 7; for all the latter are exact duplicates of each other, while no two of the pairs 51, 52 are alike. This is evident upon the inspection of Fig. 9, where it may be noted that the gear 51 of the pair nearest to the motor-2 is smaller than its associated gear 52, while at the opposite end of the driving shaft, the gear 51 is larger than its associated gear 52, and between such limits is a substantially uniform gradation from the one extreme to the other.

It is absolutely essential that a governing device be provided for the interrupting devices or rotors, in order to maintain the instrument at pitch, and especially when the siren tones are reinforced by resonators, tuning forks or ,tuned strings. To do this, I provide a governor comprising weighted arms 53 (Fig. 9) pivotally carried by a preferably horizontal revolving table 54 geared to the shaft 50; such arms pressing the friction pads 55 by centrifugal force against the inner periphery of a fixed drum 56; the retracting springs 57 tending to retain the pads out of contact. But in whichever way actuated, whether by a single driving shaft, as in Fig. 9, or by duplicate pairs of gears joining rotor to rotor, as in Fig. 1, it is essential that the rotative speed of each rotor shall bear the ratio of one to the twelfth root of two relative to the rotor whose inteeth are possible, and the object to be at-.

tained is hence to find a whole number which when multiplied by the twelfth root of two will produce a whole number or a close approximation thereto. Accordingly, I multiply the twelfth root of two, (that is,

1.05946+'), by the integers, and also by 10, 20, 30, and successive tens up to the limit or number of teeth which it is feasible to use in the gears, such'limit being set by the size of the gears and the pitch of the teeth. This limit should not exceed 300 teeth per gear. An inspection of the table produced by the method above set forth shows that within the aforesaid practical limit there is no ratio above or below that of 196 to 185 which nearly approximates the same in accuracy. This ratio is unique in its exceedingly close approximation to the desired twelfth root of two, and these numbers are the only ones in the entire range of those available which provide practically perfect gears for the purpose indicated. I have therefore adopted for the gears 6 and 7, respectively, 196 and 185 teeth, these numbers being indicated in Fig. 2 by numerals, and by conventionalized teeth through one-seventh of the circumference of gear 6 and one-fifth of the circumference of gear 7.

hat I claim is 1. A plurality of sirens adapted to produce a series of pulsations having the respective frequencies of the vibrations of the notes of a musical scale; and means for re inforcing said pulsations, said means comprising a series of reinforcing members each tuned to the pulsation it reinforces, all in combination.

2. The combination of a plurality of siren rotors adapted to produce pulsations having the respective frequencies of the vibrations of the notes of a musical scale; means for re inforcing said pulsations, said means comprising a series of reinforcing members each tuned to the pulsation it reinforces; and speed-governing means for said rotors.

3. The combination of a series of disks each having several annular rows of blast openings, the numbers of openings of the respective rows forming a geometrical series;

means for delivering a fluid under pressure to said openings; and means for rotating said disks with angular velocities increasing regularly throughout the series, the ratio between the velocities of successive disks being everywhere substantially one to the twelfth root of two.

'4. The combination of a series of duplicate disks having each several annular rows of blast openings, the numbers of such openings forming a geometrical series; means for delivering fluid under pressure to such openings; and means for rotating said disks, said means embracing a pair of gears connecting each disk to the one next higher in rotative speed, one gear in each pair having one hundred and eighty-five teeth and the other one hundred and ninety-six teeth.

- In testimony whereof I have affixed my signature, in presence of two witnesses.

EDWVARD G. THOMAS. Y Witnesses:

GEORGE W. FLINT,- MAY E. CHURCH. 

